He took some drags during the informal and formal scrums, as can be seen above. A reporter then asked for clarification.

“It’s CBD,” Diaz said. “It helps with the healing process and inflammation and things like that, so you want to get these for before or after the fights, in training. It’ll make your life a better place.”

CBD, or cannabidiol, is one of 113 active cannabinoids found in cannabis (marijuana). It’s been used in the treatment of schizophrenia, epilepsy and other conditions, and clinical studies show a lack of psychoactivity like a user would get with traditional marijuana.

Cannabinoids are banned “in competition” by the Nevada State Athletic Commission and by the UFC’s drug-testing partner, the U.S. Anti-Doping Agency, according to combat-sports lawyer Erik Magraken of combatsportslaw.com. Although the UFC-USADA’s in-competition period ends six hours after a fight, Diaz could be in the clear from a drug-testing perspective, according to Magraken:

“Assuming Nate Diaz provided a post bout sample to the NSAC (assuming they wished to collect one) before vaping and assuming that sample come sback negative than this escapade will not amount to an NSAC anti-doping violation.

“Interestingly, if USADA wishes to collect a sample in the hours following the vaping, depending on the substance being ingested, Nate’s choice may prove problematic.”

Like his brother and fellow UFC fighter Nick Diaz, Nate Diaz is an outspoken cannabis proponent. In some pre-fight social-media postings, he specifically championed CBD oil as beneficial to athletes.